Each VSI Certified Installer must demonstrate the knowledge and skills to properly install vinyl siding and accessories, based on the industry standard, ASTM D4756. When
you hire an installer certified through VSI’s program, you can be confident that he or she knows how to:

Correctly fasten the siding to allow for vinyl’s normal expansion and contraction properties and keep it straight and secure on the wall.

Properly prepare the area around doors, windows, and other openings to prevent water infiltration.

Pay attention to the details that will give your home a beautiful appearance that will last over time.

To become a VSI Certified Installer, candidates must have a minimum of two years of installation experience, attend VSI’s rigorous course, and pass the VSI Certified Installer
examination. All VSI Certified Installers must apply for recertification every three years, to ensure that they stay abreast of the latest application techniques.

Bosteter Windows and Siding is a Certified Lead Safe Company with the EPA, Minnesota Department of Health. If you’re concerned that lead may be present during your next home improvement project rest assured that all appropriate lead safe practices will be followed. At Bosteter Windows and Siding we treat all pre-1978 homes as if lead is in fact present. We take this extra step to assure the safety of our valued customers.

Bosteter Windows and Siding has been certified as a “Mastic Elite Contractor” by Mastic Home Exteriors, one of the nation’s leading manufacturers and suppliers of high quality siding materials. Of the thousands of home contractors across the United States, less than 400 companies have received this honor.

How We Became a Mastic Elite Contractor for Winona, Minnesota

In order to attain this lofty status with Mastic, Bosteter Windows and Siding had to meet specific criteria and then be nominated by a Mastic regional sales manager. Among the criteria we meet are:

Have Vinyl Siding Institute (VSI) certified installers on our staff

Successfully complete two Mastic factory training courses

Have at least five years experience in the siding industry

Have a Better Business Bureau (BBB) rating of 90% or better

Having met or exceeded all of these criteria, Bosteter Windows and Siding has been officially certified by Mastic Home Exteriors as a “MasticElite Contractor.” We are the only Winona area siding contractor to receive this designation

What It Means for You

As a Mastic Elite Contractor, Bosteter Windows and Siding can offer our customers additional benefits when they purchase the complete Mastic elite siding system, including Mastic’s industry-leading warranty program. It is one more way that we are delivering superior service to our Minnesota vinyl siding customers.